Re: XPS 9360 SATA (IDE vs AHCI) configuration from factory
When you say "XPS 9360", you're referring to the XPS 13 9360 released in the last 1-2 years, correct? If so, the options are AHCI and RAID. IDE is well over a decade old at this point, so you definitely wouldn't have that option on an even remotely modern system. As for performance though, Dell ships all of their systems configured in RAID mode for reasons mostly having to do with history. RAID mode allows ordering systems that have a spinning drive and a low-capacity SSD cache module, with the latter accelerating the performance of the former. That configuration isn't possible on the XPS 13 though. And second, for systems that use an NVMe SSD, RAID mode allows them to be used even with OSes that don't natively support NVMe, such as Windows 7 -- but the XPS 13 9360 doesn't support Windows 7 for other reasons anyway, which is why I said the reasons mostly have to do with history. In terms of performance impact, I compared an XPS 13 9360 with a Samsung 960 Evo installed, and AHCI vs RAID didn't make a consistently repeatable difference in benchmarks. In any case, the main bottleneck with a modern SSD will be the XPS 13 itself, since it runs its NVMe interface in power saving mode, which limits max sequential throughput to around 1.8 GB/s, even though modern NVMe SSDs can exceed 3 GB/s.
When you say it takes 15 seconds to "fire up", what conditions are you starting with, and what do you define as fully fired up? For example, are you starting with a system that was fully shut down, hibernated, or put to sleep? And are you stopping the timer when you see the logon screen or after your entire user profile seems to have loaded, including all system tray icons? Those factors and obviously the software you've got installed on your system (particularly third-party anti-malware solutions) can significantly affect boot time.